1. Field of the Invention
The present invention is included in a technical field of, for example, semiconductor device fabrication, and more specifically, relates to a processing system including an image pickup means for monitoring units on a transfer apparatus for transferring a substrate.
2. Description of the Related Art
In a photoresist processing step in semiconductor device fabrication, for example, a resist solution is supplied to a substrate such as a semiconductor wafer (hereinafter, referred to as “a wafer”) or the like to form a resist film, a predetermined pattern is exposed, and thereafter a developing solution is supplied to the wafer to perform developing processing. When such a series of processing is performed, a coating and developing processing system is used conventionally.
The coating and developing processing system comprises processing units for separately performing a series of processing necessary for coating and developing processing for a wafer, for example, hydrophobic processing (adhesion processing) for enhancing fixedness of a resist, resist coating processing for performing coating of a resist solution, heating processing for heating the wafer after the coating of the resist solution to cure a resist film, heating processing for heating the wafer after exposure at a predetermined temperature, developing processing for performing developing processing for the wafer after exposure, and the like.
These units have points to be monitored respectively, and thus the number of points to be monitored is considerably large in the whole coating and developing processing system including many units. For instance, in a spin-coat type of resist coating unit and developing unit, it is necessary to monitor whether a processing solution such as a resist solution, a developing solution, or the like is supplied onto the center of a rotated substrate. At that time, from the viewpoint of resist solution saving and uniform coating, it is necessary to monitor the state of the processing solution which extends by centrifugal force, especially the condition of the edge of the extending solution spreading out. Moreover, it is also necessary to monitor a liquid drip which occurs at the tip of a nozzle for supplying the processing solution. In a heating processing unit and a cooling processing unit, it is necessary to monitor whether the wafer is placed at a predetermined position on a hot plate or a cooling plate.
Therefore, it is considered, for instance, that an image pickup means such as a CCD camera is provided at each position which needs to be monitored in each processing unit, and that the above monitoring is performed based on the image pickup result. However, there is a problem that the number of positions to be monitored is large, and thus the number of components such as a CCD camera and the like is quite large. Moreover, there is another problem that since it is strongly demanded to miniaturize and thin each processing unit, a space for provision of the image pickup means such as a CCD camera or the like can not be secured.